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 A299505 Numbers of the form x^4 + y*x^3 + y^2*x^2 + y^3*x + y^4, where x and y are positive integers. 0
 5, 31, 80, 121, 211, 341, 405, 496, 781, 1031, 1280, 1441, 1555, 1936, 2101, 2511, 2801, 3125, 3355, 3376, 4141, 4651, 4681, 5261, 5456, 6480, 6505, 6841, 7381, 7936, 8431, 9031, 9801, 9881, 11111, 11605, 12005, 12496, 13981, 14251, 15961, 16105, 16496, 17091, 17891 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..45. PROG (Julia) function isA299505(n) n % 5 >= 2 && return false n == 5 && return true K = Int(floor(5.383*log(n)^1.161)) M = Int(floor(2*sqrt(n/3))) for k in 3:K for y in 2:M, x in 1:y n == x^4+y*x^3+y^2*x^2+y^3*x+y^4 && return true end end return false end A299505list(upto) = [n for n in 1:upto if isA299505(n)] println(A299505list(18000)) CROSSREFS Cf. A024614, A002649 (subsequence of primes). Sequence in context: A078686 A031908 A139862 * A102732 A213068 A138657 Adjacent sequences: A299502 A299503 A299504 * A299506 A299507 A299508 KEYWORD nonn AUTHOR Peter Luschny, Mar 02 2018 STATUS approved

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Last modified June 4 02:25 EDT 2023. Contains 363118 sequences. (Running on oeis4.)